The problem of servomotor control is ubiquitous. Automated equipment must run as fast as possible and the time required to position a servomotor is largely lost time. Such diverse tasks as the testing of a semiconductor device and a positioning of a computer disk drive head are dependent, in part, on improvements in servomotor control for increases in the speed of the task.
Servomotors have historically been controlled by analog systems which do little to optimize the speed with which the servomotor is driven to a particular position. More recently, digital control systems have replaced analog ones. The advent of inexpensive microprocessors and memory has allowed the development of control schemes which adapt to current conditions in a relatively complex manner. However, the application of control theory to servomotor control and the development of highly optimized servomotor control schemes is a very recent development and is far from complete.
A particular area of interest is that of DC servomotors of the armature controlled, low inertia, low inductance type. Relatively accurate models of the behaviors of such motors have been available for at least a decade. Furthermore, modern control theory is available to devise optimized control algorithms for such motors. However, there has not been available a high speed servomotor controller based on the use of modern techniques. The theoretical limit on the speed with which such a servomotor may be positioned has not been approached.